https://hdl.handle.net/10259/5498 2026-10-12T16:48:43Z 2026-10-12T16:48:43Z Vélez Martín, Sergio Bretzel, Tamara Pöter, Rhea Berwind, Matthew F. Trommsdorff, Max https://hdl.handle.net/10259/12205 2026-10-01T00:05:27Z 2026-08-01T00:00:00Z

IoT-based monitoring workflow for continuous analysis of apple ripening delay and maturation patterns under agrivoltaics Vélez Martín, Sergio; Bretzel, Tamara; Pöter, Rhea; Berwind, Matthew F.; Trommsdorff, Max Agrivoltaic systems, combining solar energy generation with agricultural activities, offer a sustainable approach to maximising land efficiency. However, these systems can present challenges, such as potential shading effects that may impact fruit quality or crop yields. This study evaluated the impact of overhead agrivoltaic systems on apple (Malus domestica L. cv. Gala) ripening and maturation patterns in a temperate orchard near Lake Constance, Germany. Experiments compared apples grown under conventional conditions (control) with those under agrivoltaic setups equipped with semi-transparent photovoltaic panels utilizing spatially distributed cells for 40% light transparency installed with a 70% ground-coverage ratio. Key metrics, including fruit diameter, length, volume, and BBCH phenology stages, were monitored throughout the 2024 growing season. An IoT-based monitoring workflow was developed, combining fixed RGB image acquisition, automatic apple detection, colour-based ripening quantification, and time-series analysis to monitor visible maturation dynamics under field conditions. Results indicated that apples under agrivoltaic conditions showed delayed visible red-colour development, reaching comparable image-derived colour-maturity thresholds approximately 10–12 days later than the control group. On September 13 (harvest), no significant differences were found in mean length, while the diameter of agrivoltaic apples was significantly smaller (65.59 mm versus 70.98 mm), indicating slightly smaller dimensions under shaded conditions. Fruit volume and weight were approximately 16% lower under agrivoltaic conditions, averaging 161.16 cm3 (138.6 g) versus 191.58 cm3 (164.8 g) in the control. The delayed visible maturation was consistent with reduced light availability under the solar panels, although fruit-level light availability and physiological maturity indicators were not directly measured. These findings suggest that overhead agrivoltaic systems can significantly delay apple phenology and fruit maturation. Depending on the agricultural goals, the desired harvest timing and the cultivar, this may be challenging or beneficial, e.g., if it adapts the crop against climate change impacts or other factors such as local climate conditions, latitude and geographic region, and market demand. Integrating IoT-based monitoring with machine learning enhances the precision of agricultural assessments, providing valuable data for managing the effects of agrivoltaic systems on crop development.

2026-08-01T00:00:00Z Urbaneja Miguel, Álvaro Torija López, Alba Carrancho Alonso, Ángel Iriarte Avilés, Eneko González Moreno, Sara González Martín, José Manuel Trigo López, Miriam Vallejos Calzada, Saúl https://hdl.handle.net/10259/12054 2026-09-09T09:27:18Z 2026-07-31T00:00:00Z

UBU-Polymers Research Group 12122025 Urbaneja Miguel, Álvaro; Torija López, Alba; Carrancho Alonso, Ángel; Iriarte Avilés, Eneko; González Moreno, Sara; González Martín, José Manuel; Trigo López, Miriam; Vallejos Calzada, Saúl The dataset contains all raw data of the work "Atmosphere-controlled thermal processing enables tunable optical properties via iron-oxide phase engineering in natural silicate materials"

2026-07-31T00:00:00Z Urbaneja Miguel, Álvaro Torija López, Alba Carrancho Alonso, Ángel Iriarte Avilés, Eneko González Moreno, Sara González Martín, José Manuel Trigo López, Miriam Vallejos Calzada, Saúl https://hdl.handle.net/10259/11978 2026-08-28T00:05:21Z 2026-05-29T00:00:00Z

Atmosphere-controlled thermal processing enables tunable optical properties via iron-oxide phase engineering in natural silicate materials Urbaneja Miguel, Álvaro; Torija López, Alba; Carrancho Alonso, Ángel; Iriarte Avilés, Eneko; González Moreno, Sara; González Martín, José Manuel; Trigo López, Miriam; Vallejos Calzada, Saúl Controlled-atmosphere thermal processing was investigated as a method to engineer iron-oxide phase assemblages in iron-bearing silicate materials. Natural sandstone was heated between 200 and 1000 °C under air, N2 and CO2 atmospheres to evaluate how oxygen partial pressure governs redox transformations and the resulting macroscopic optical behaviour. The treatments produced a wide and reproducible range of optical responses from a single starting material. Colour evolution, quantified in the CIELAB space, correlates with bulk mineral transformations. Oxidizing conditions stabilize hematite-dominated assemblages and generate red hues, whereas reduced-oxygen atmospheres promote magnetite formation and progressive darkening. Rock-magnetic measurements identify atmosphere-dependent phase assemblages, including a high-coercivity iron oxide under strongly oxidizing conditions. The magnetic response mirrors the optical evolution, indicating that colour development originates from internal phase transformations. Compressive strength remained within the same order of magnitude as the untreated material across the studied conditions, indicating no catastrophic mechanical degradation. These results show that oxygen availability acts as a key processing variable controlling iron-oxide stability and optical response. The study establishes a process-based approach for tuning optical properties in mineral materials through atmosphere-controlled thermal processing without chemical additives. Unlike previous studies focused on temperature-driven effects or isolated observations, this work demonstrates a reproducible process-based approach to tune optical properties in natural silicate materials through controlled atmosphere engineering.

2026-05-29T00:00:00Z Revilla Cuesta, Víctor Hernando Revenga, Manuel Martín Para, Ismael Skaf Revenga, Marta Ortega López, Vanesa https://hdl.handle.net/10259/11484 2026-03-21T01:05:41Z 2026-02-01T00:00:00Z

Effectiveness of Temporal Survey-Based Programs for Teaching Critical Thinking Skills in Engineering Courses: Analysis of Final Assessments Revilla Cuesta, Víctor; Hernando Revenga, Manuel; Martín Para, Ismael; Skaf Revenga, Marta; Ortega López, Vanesa Peer- and self-critical skills are key to properly performing engineering work, as they allow engineering students to develop critical thinking regarding the quality standards required in this professional field. This research aimed to determine whether educational experiences based on temporal survey-based programs enabled the successful development of these skills in students enrolled in six courses in the final years of their engineering degrees. To this end, an educational experience of such a nature was implemented throughout a complete academic year, aimed at fostering peer- and self-critical skills through continuous formative assessment. The experience involved six student presentations evaluated by both teachers and peers using a Likert-scale survey encompassing four dimensions: explanatory ability, file quality, attitude, and overall assessment. Subsequently, these assessments were provided to students to encourage reflection on the scores assigned and their own work. The results revealed strong alignment between teacher and peer evaluations, with average deviations below 7%, demonstrating effective development of peer-critical competences. These results were also verified by means of analyses of variance. The greatest consistency was found in “explanatory ability” and “overall assessment,” while “file quality” and “attitude” showed wider variability, experience playing a key role in their precise evaluation. Peer evaluations tended to be more uniform than teachers’, reflecting students’ limited experience in discerning subtle performance differences. Additionally, 30% of students expressed willingness to repeat their final presentation to achieve a higher grade, evidencing substantial self-critical reflection. Qualitative analysis conducted through deductive cross-coding indicated that this motivation stemmed from both intrinsic self-improvement and peer-related responsibility. Overall, the results confirm that sustained peer- and self-assessment activities can effectively cultivate critical thinking skills among engineering students, although continuous practice is required to consolidate these competences. Future research could explore the more adequate course types, and students’ ages to perform such kind of educational experiences.

2026-02-01T00:00:00Z